Fever Pitch: Unpicking the Flat vs Pitched Roofing Debate

It’s one of the most important considerations in new-build architecture – whether to finish the property with a pitched or flat roof. But it’s also a decision that inspires hotly-contested discussions on the pros and cons of each option, with advances in materials meaning the choice is wider than ever. In this article, George King, Divisional Managing Director at SIG Exteriors, gets to the heart of the debate, and looks at the solutions currently available to architects and specifiers.


Trends and standards have moved on considerably since the days when ‘flat roof’ was merely a byword for garages and extensions. Indeed, take a walk around any city in the UK – or switch on any of the myriad architectural ‘dream home’ shows on television – and you’ll see some visually stunning properties that have utilised this method of insulating and protecting a home.

For the homeowner of today, to whom aesthetics and kerb appeal is a key consideration when buying or selling a property, flat roofs can represent a stylish yet uniquely modern finish for a house, just as much as the pitched roof alternative. Both have their benefits. By taking these into consideration, architects and specifiers will be best placed to provide their clients with advice and guidance to help meet their project’s requirements – and pockets.

On the pitch

For many years, the pitched roof has come to dominate our mental image of what a ‘traditional’ house looks like. The staple of new-build developments nationwide, pitched roofs have long been the preferred choice for many architects, who cite the reliability and durability of the system. Representing up to 30% of the visible building, a pitched roof can significantly enhance the aesthetics of a property, with the use of coloured tiles or slates affording a sense of character and uniqueness.

But the benefits go beyond looks. Pitched roofs have a well-earned reputation for durability and weather resistance – a key consideration for a country with a climate as diverse as the UK’s. Indeed, once built, pitched roofs should require little to no maintenance.

The angled slope of the roof eliminates the risk of pooling, serving as a highly efficient drainage system for what can be significant quantities of water. What’s more, a pitched roof creates additional usable space for a property whether it’s used for simple storage or, with some further investment, a loft extension, providing an extra bedroom or home office (a key consideration in these ‘remote working’ times).

In terms of additional considerations for pitched roofing, they can be costlier to install than their flat roof counterparts due to the structural complexity and the additional labour and materials required. However, when taking into account the potentially longer lifespan of a pitched roof, it is worth remembering that the extra investment at the outset can lead to greater ROI further down the line.

Flat out

The image of flat roofs has come a long way in the past 20 years thanks to innovations and new materials, increasing durability and bringing it closer in line with pitched roofs.

When considering a flat roof for a project, there are a number of points which require careful thought, including the material the structural deck is made from; is it a cold, warm or inverted roof; what ventilation is required; and what finish are you looking to achieve?

Options for the roof deck range from OSB (oriented strand board) and metal to concrete. OSB is the most readily available and easiest to fit, while the longer ‘design life’ of concrete is offset by a slower construction process and the need to use a specialist contractor.

A cold deck roof has insulation in the ceiling void, reducing installation time. In a warm roof, the insulation sits above the void, making it more energy efficient than a cold roof.

With an inverted roof, the insulation is above the waterproofing layer – usually a liquid-applied membrane. It can be used as a recreational space with paving but must be capable of supporting both dead and live loads.

For waterproofing, EPDM rubber membrane – originally produced for the commercial market – is an increasingly popular choice. With unmatched weatherability, it’s also suitable for ‘green’ roof systems. Alternatives include ‘torch-on’ bituminous membranes, modern mastic asphalt, single-ply, liquid coatings and GRP composite. All can offer warranties of up to 20 years, some longer.

Be it aesthetics, cost or durability; both systems ultimately offer their own unique benefits and strong points. For the specifer of today, the quality and popularity of each system mean there is a wide range of affordable, easy-to-install materials to choose from – making it easier than ever before to give a project the perfect finish.

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